334 
Fig. 111—Nymph of Isoperla burksi. 
except tenth; posterior margin of each ter- 
gite with numerous short, stout, pale 
setae; some scattered short, stout setae 
together with fine hairs on central area 
of tergites. Cerci long, many segmented, 
segments progressively longer from base to 
apex; a longitudinal row of long fine setae 
on dorsal surface of apical segments in 
addition to smaller spinelike ones encir- 
cling apex of each segment. 
Approximately mature specimens with 
body length of 11 mm. 
No thoracic, anal or submental gills. 
Nymphal and exuvial records are as fol- 
lows. 
I_Linois.—HeErop, Gibbons Creek: April 19, 
1937, H. H. Ross=&sC730. Mohr, 1 nymph. 
Gotconpa: May 13, 1939, B. D. Burks & G. 
T. Riegel, 1 exuvia. EDDYVILLE, Lusk Creek, 
Pope County: April 30, 1940, 2 nymphs; May 
1, 1940, 1 nymph; May 9, 1940, 2 nymphs; 
May 24 and June 1, 1940, many exuviae; all 
collected by B. D. Burks & C. O. Mohr. 
This is another new species first found 
ItLinois NaturAL History SURVEY BULLETIN 
V ol. 22; Aree 
as a nymph and, because of distinctive 
features of nymph, recognized as new to 
the Illinois faunal list before adult was 
reared. Rearings and collection of ma- 
terial prove it to be a previously unde- 
scribed species. The combination of | 
nymphal and adult characters separates it 
from all other species of Isoperla. Al- 
though much smaller than ventralis 
(Banks), it somewhat resembles this spe- 
cies in general color pattern of adult. In 
the nymph, the transverse bands on ab- 
dominal tergites place it with such species 
as marlynia Needham & Claassen (= clio 
of American authors). 
I take pleasure in naming this species 
for Dr. B. D. Burks, Assistant) ama 
mologist on the staff of the Illinois Nat- 
ural History Survey, who has assisted with 
the collection and rearing of stonefly ma- 
terial in Illinois and elsewhere. 
Isoperla lata new species 
Mate.—Basic color brownish to black. 
Dorsum of head with a small yellowish 
spot anterior to median ocellus, another 
yellowish spot in ocellar triangle, and with 
a large yellowish area on posterior part 
of head running forward on each side be- 
tween compound eyes and lateral ocelli, 
fig. 112. Pronotum with a broad, median, 
longitudinal, yellowish stripe, much nar- 
rower at anterior end than posterior end, 
fig. 112; areas each side of stripe brown 
to black. Mesonotum and metanotum 
essentially brown to black. Abdomen 
brown to black, with two short, pale, 
longitudinal stripes on the two basal ter- 
gites. Legs, antennae and anal cercl 
brownish. 
Head slightly wider through compound 
eyes than width of pronotum; lateral 
ocelli farther distant from one another 
than each is from median ocellus; distance 
between each compound eye and lateral 
ocellus about the same as between lateral 
ocellus and median ocellus. 
Pronotum approximately quadrangular, 
broader than long, a distinct pattern 0 
raised rugosities on surface each side of 
pale, median, longitudinal stripe, fig. 112. 
Legs with first and second tarsal seg- 
ments together shorter than third, first 
tarsal segment much longer than second. 
Wings slightly suffused with brownish, 
veins uniformly dark brown. 
